|Publication number||US4931764 A|
|Application number||US 07/290,011|
|Publication date||Jun 5, 1990|
|Filing date||Dec 27, 1988|
|Priority date||Dec 27, 1988|
|Also published as||CA1327896C|
|Publication number||07290011, 290011, US 4931764 A, US 4931764A, US-A-4931764, US4931764 A, US4931764A|
|Inventors||Robert D. Gaston|
|Original Assignee||Ford Motor Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (9), Non-Patent Citations (1), Referenced by (52), Classifications (13), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention is directed to the field of liquid fuel tank monitoring systems and more specifically to the area of resistor cards employed in such systems.
2. Description of the Prior Art
In conventional liquid fuel level indicating systems for automotive vehicles such as shown in the 1987 Taurus/Sable shop manual published by the Ford Motor Co., Section 33-20, a variable resistor has its setting controlled by a float. The float is connected to a rod which is pivotally connected to sweep a wiper contact over a resistive card and thereby select a value of resistance indicative of the liquid fuel level within the tank.
A conventional resistor card 100, which is typical of those used in Ford Motor Co. vehicles, is shown in FIGS. 1A and 1B. That prior art resistor card 100 comprises a substrate 10 with a plurality of metallized conductors in groups 20, 22 and 24 depositied thereon. Each of the metallized layers is deposited on the substrate 10 so as to be electrically isolated, one from the other. A thick film resistive (ink) material 30, 32 and 34 is deposited in precise areas so as to interconnect respective groups of metallized layers 20, 22 and 24 to thereby provide precise resistant values between the metallized layers empirically determined by the shape and volume of the associated tank for which the fuel level is being measured. As can be seen in FIG. 1B, a wiper contact arm 40 makes direct contact at point 42 against the metallized layer. Although not shown, the wiper contact 40 traces an arcuate path corresponding to the arcuate arrangement of the metallized layers 20, 22 and 24 and makes contact with at least one of those layers throughout its path range.
When the card 100 is immersed within the liquid fuel, the fuel acts as a lubricant between the wiper 40 and the metallized contact layer 20, 22, or 24. However, when the card is dry because the level of the fuel in the tank has dropped below the location of the card 100, the wiper causes some wear to develop on the metallized layers. This problem has been noticed when vehicles are delivered cross-country from the factory, by rail or truck, where the fuel level in the tank is constant and the vibration caused by the transporting means produces fuel movement. Such movement causes corresponding and repeated movement of the wiper and significant wear on the metallized layers, with occasional wear-through to the substrate. In the event of wear-through, dead spots, (discontinuities) appear in the resistor card 100 and the fuel gauge observed by the operator is adversely affected when the wiper contact is in contact with such dead spots.
The present invention is intended to overcome the problems with conventional fuel sender resistor cards by providing a material overlaying the metallized conductor paths that acts to inhibit wear without significantly altering the electrical characteristics of the card.
FIG. 1A is a plan view of the prior art resistor card discussed above.
FIG. 1B is cross-sectional view of the prior art resistor card shown in FIG. 1A.
FIG. 2A is a plan view of a resistor card embodiment of the present invention.
FIG. 2B is a cross-sectional view of the resistor card shown in FIG. 2A.
In FIGS. 2A and 2B the present invention is shown as a deposition of a thick film resistive material 36 deposited on the pad portions of the individual metallized conductor layers 20, 22, and 24 lying in the sweep path of the conductive wiper 40. Those pads are a series of radial strips formed in an arcuate path so that the sweep of the contact wiper 40 maintains electrical contact with at least one pad during its sweep between the high and low levels of liquid within the associated tank.
The resistive thick film material 36 is the same as that employed for areas 30, 32 and 34 and is commercially available from several sources including E. I. DuPont Denemours & Co. Inc under the trade name BIROX in various formulations for resistance selection. The thick film material when distributed in areas 30, 32 and 34 in the preferred embodiment provides a selection of resistance values in a range of from 15 ohms (empty) to 160 ohms (full). However, the resistance between the contact wiper 40 at point 42' and the underlying pad is on the order of 0.01 ohms. Therefore, the addition of the thick film material 36 has no significant affect on the electrical characteristics of the card 100.
The thick film material 36 is commonly referred to as an "ink" and is deposited onto the metalized layers with conventional silk screen techniques. It is subsequently heat cured according to the manufacturers recommendations and then trimmed as necessary to ensure that the deposited material coverage corresponds to the pad area of the respective metallized conductors 20, 22 and 24. It has been found that the use of the resistive thick film material 36 on the conductive pads, provides a significant degree of protection to the metallized layers from the conductive wiper 40 that was not available otherwise. Thicknesses of the metallized layers in the described embodiment are on the order of 0.012 mm, while the thickness of the thick film resistive material is also on the order of 0.012 mm.
It is believed that the inclusion of silica and alumina in the thick film resistive material is a significant deterent to frictional wear by the conductive wiper 40, since the occurance of the wear-through problem appears to be solved. In this manner, the thick film layer 36 acts as a protective coating while at the same time providing a minimum resistance between the contact point 42' and the metallized conductor 22.
It will be apparent that many modifications and variations may be implemented without departing from the scope of the novel concept of this invention. Therefore, it is intended by the appended claims to cover all such modifications and variations which fall within the true spirit and scope of the invention.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3102990 *||Dec 11, 1961||Sep 3, 1963||Beckman Instruments Inc||Variable resistor contact|
|US3206702 *||Jul 1, 1963||Sep 14, 1965||Beckman Instruments Inc||Electrical resistance element|
|US3457537 *||Nov 23, 1966||Jul 22, 1969||Hines Paul J||Flexible resistance element film|
|US4237442 *||Feb 26, 1979||Dec 2, 1980||Carrier Corporation||Electrical resistance element for variable resistance devices|
|US4243969 *||Apr 17, 1979||Jan 6, 1981||Preh, Elektrofeinmechanische Werke Jakob Preh Nachf. Gmbh & Co.||Layer resistor element|
|US4284969 *||Nov 9, 1979||Aug 18, 1981||Clarostat Mfg. Co., Inc.||Potentiometer|
|US4318075 *||Aug 7, 1980||Mar 2, 1982||Vdo Adolf Schindling Ag||Thick-film potentiometer|
|US4345235 *||Sep 12, 1980||Aug 17, 1982||Spectrol Electronics Corporation||Variable resistance device having a resistance element with laser cuts|
|US4409295 *||Jan 21, 1982||Oct 11, 1983||Olin Corporation||Electrical connector material|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5126716 *||Nov 24, 1989||Jun 30, 1992||Motorola, Inc.||Artificial resistive card|
|US5272918 *||Jun 30, 1993||Dec 28, 1993||Ford Motor Company||Pivotal liquid level sensor assembly|
|US5341679 *||May 14, 1993||Aug 30, 1994||G.T. Products, Inc.||Resistor card fuel level sender with float arm actuator|
|US5364705 *||Jun 25, 1992||Nov 15, 1994||Mcdonnell Douglas Helicopter Co.||Hybrid resistance cards and methods for manufacturing same|
|US5494180 *||Sep 26, 1994||Feb 27, 1996||Mcdonnell Douglas Helicopter Company||Hybrid resistance cards and methods for manufacturing same|
|US5554965 *||Nov 2, 1994||Sep 10, 1996||The Erie Ceramic Arts Company||Lubricated variable resistance control having resistive pads on conductive path|
|US5644321 *||May 22, 1995||Jul 1, 1997||Benham; Glynda O.||Multi-element antenna with tapered resistive loading in each element|
|US5743136 *||Sep 27, 1995||Apr 28, 1998||Ford Motor Company||Fluid level sensor with resistive and conductive layers|
|US5746088 *||Feb 9, 1996||May 5, 1998||General Motors Corporation||Fuel system low current rheostat|
|US5943025 *||Sep 3, 1997||Aug 24, 1999||Megawave Corporation||Television antennas|
|US5959586 *||Jul 18, 1997||Sep 28, 1999||Megawave Corporation||Sheet antenna with tapered resistivity|
|US6021668 *||Nov 18, 1997||Feb 8, 2000||General Motors Corporation||Indicator system|
|US6025772 *||Jul 8, 1998||Feb 15, 2000||Chen; Jack||Potentiometer|
|US6127916 *||May 8, 1997||Oct 3, 2000||Cts Corporation||Fuel system low current rheostat|
|US6212950||May 28, 1997||Apr 10, 2001||Cts Corporation||Glass interlaced fuel system low current rheostat|
|US6369690 *||Mar 6, 2000||Apr 9, 2002||Jack Chen||Potentiometer|
|US6483421||Nov 5, 1999||Nov 19, 2002||Siemens Vdo Automotive Ag||Carrier substrate with a resistor track|
|US6588288 *||Sep 19, 2000||Jul 8, 2003||Rochester Gauges, Inc.||Resistive element structure for a sender assembly of a gauge|
|US6751848 *||Jun 27, 2002||Jun 22, 2004||Yazaki Corporation||Method for adjusting a resistance value of a film resistor|
|US6828898||Apr 3, 2003||Dec 7, 2004||Cts Corporation||Fuel tank resistor card having improved corrosion resistance|
|US7038473||Oct 23, 2002||May 2, 2006||Siemens Aktiengesellschaft||Method and apparatus for measuring a fluid level and a motor vehicle provided with such apparatus|
|US7079005||Nov 30, 2004||Jul 18, 2006||Cochran Gary D||Mechanically buffered contact wiper|
|US7091819||Jun 22, 2005||Aug 15, 2006||Ti Group Automotive Systems, L.L.C.||Variable resistor card for a fuel level sensor|
|US7100442 *||Oct 4, 2000||Sep 5, 2006||Alfmeier Prazision Ag. Baugruppen Und Systemlosungen||Transmitter for level in a fuel tank of a motor vehicle|
|US7654281||Oct 31, 2007||Feb 2, 2010||Rochester Gauges, Inc.||Gauge assembly having a stop fill device|
|US7690323||Apr 6, 2010||Rochester Gauges, Inc.||Gauge head assembly with non-magnetic insert|
|US7726334||Aug 17, 2007||Jun 1, 2010||Rochester Gauges, Inc.||Service valve assembly having a stop-fill device and remote liquid level indicator|
|US7921873||Apr 12, 2011||Rochester Gauges, Inc.||Service valve assembly having a stop-fill device and a liquid level indicating dial|
|US20030000071 *||Jun 27, 2002||Jan 2, 2003||Yazaki Corporation||Resistance value adjusting method|
|US20040196137 *||Apr 3, 2003||Oct 7, 2004||Ronald Dedert||Fuel tank resistor card having improved corrosion resistance|
|US20050001636 *||Oct 23, 2002||Jan 6, 2005||Wolfgang Sinz||Method and apparatus for measuring a fluid level and a motor vehicle provided with such apparatus|
|US20050116809 *||Nov 30, 2004||Jun 2, 2005||Cochran Gary D.||Mechanically buffered contact wiper|
|US20060016256 *||Jun 27, 2005||Jan 26, 2006||Alfmeier Prazision Ag, Baugruppen Und Systemlosungen||Filling level sensor for a tank|
|US20090107393 *||Oct 31, 2007||Apr 30, 2009||Rochester Gauges, Inc.||Gauge head assembly with non-magnetic insert|
|US20100229964 *||Aug 18, 2007||Sep 16, 2010||Rochester Gauges, Inc.||Service valve assembly having a stop-fill device and remote liquid level indicator|
|US20110074448 *||Sep 25, 2008||Mar 31, 2011||Petr Zeman||Potentiometer|
|DE4414944A1 *||Apr 28, 1994||Jan 19, 1995||Ford Motor Co||Flüssigkeitspegel-Sensoranordnung|
|DE4414944C2 *||Apr 28, 1994||May 7, 1998||Ford Motor Co||Sensoranordnung zum Bestimmen des Flüssigkeitspegels in einem Tank|
|DE19729940A1 *||Jul 12, 1997||Feb 4, 1999||Mannesmann Vdo Ag||Printed circuit board with a slideway|
|DE19729940C2 *||Jul 12, 1997||May 2, 2002||Siemens Ag||Leiterplatte mit einer Schleiferbahn|
|DE19850936A1 *||Nov 5, 1998||May 11, 2000||Mannesmann Vdo Ag||Trägersubstrat mit einer Widerstandsbahn|
|EP0766074A2 *||Sep 16, 1996||Apr 2, 1997||Ford Motor Company||Fluid level sensor|
|EP0789231A2 *||Jan 10, 1997||Aug 13, 1997||General Motors Corporation||Fuel system low current rheostat|
|EP0828141A2 *||Jan 10, 1997||Mar 11, 1998||General Motors Corporation||Fuel system low current rheostat|
|EP0917158A1 *||Sep 14, 1998||May 19, 1999||CTS Corporation||Conductor burnishing|
|EP1271567A2 *||Jun 28, 2002||Jan 2, 2003||Yazaki Corporation||Resistance value adjusting method|
|EP1316782A1 *||Dec 3, 2001||Jun 4, 2003||Siemens Aktiengesellschaft||A method and apparatus for measuring a fluid level and a motor vehicle provided with such apparatus|
|EP2660569A1 *||Apr 16, 2013||Nov 6, 2013||Nissan Motor Manufacturing (UK) Ltd.||Fuel level sensor and method|
|WO1996024964A1 *||Jan 19, 1996||Aug 15, 1996||Megawave Corporation||Television antennas|
|WO2001054144A1 *||Jan 20, 2000||Jul 26, 2001||Jack Chen||Potentiometer|
|WO2003023793A1 *||Sep 12, 2002||Mar 20, 2003||Bourns, Inc.||Variable resistive element|
|WO2003048698A1 *||Oct 23, 2002||Jun 12, 2003||Siemens Aktiengesellschaft||A method and apparatus for measuring a fluid level and a motor vehicle provided with such apparatus|
|U.S. Classification||338/185, 338/33, 338/308|
|International Classification||H01C10/30, G01F23/36, H05K3/24, H05K1/16|
|Cooperative Classification||H01C10/305, H05K1/16, H05K3/245, G01F23/36|
|European Classification||G01F23/36, H01C10/30D|
|Mar 31, 1989||AS||Assignment|
Owner name: FORD MOTOR COMPANY, DEARBORN, MI, A DE CORP.
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:GASTON, ROBERT D.;REEL/FRAME:005036/0689
Effective date: 19881223
|Aug 2, 1993||FPAY||Fee payment|
Year of fee payment: 4
|Feb 14, 1998||REMI||Maintenance fee reminder mailed|
|Jun 7, 1998||LAPS||Lapse for failure to pay maintenance fees|
|Aug 18, 1998||FP||Expired due to failure to pay maintenance fee|
Effective date: 19980610